Image-processing apparatus, image-processing method and recording medium

ABSTRACT

In an image-processing apparatus, a digital image signal is stored in a memory, and a memory access control part entirely manages all accesses to the memory with respect to the digital image signal. An image processing part converts the digital image signal stored in the memory into an output image signal to be supplied to an imaging unit outputting a visible image based on the output image signal so that a pixel density of the output image signal is higher than a pixel density of the digital image signal read from the memory and an amount of the output image signal is less than an amount of the digital image signal stored in the memory. Accordingly, the central controlled memory is shared by a plurality of functions so as to effectively use the memory, and a high-quality image can be produced by carrying out a density conversion so as to match the pixel density.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to image processing apparatusesand, more particularly, to an image-processing apparatus which convertsread image into recordable image signal after changing the read image todigital image signals.

2. Description of the Related Art

Conventionally, multi-function apparatuses provided with a plurality offunctions, such as a so-called copy function including reading of animage, a record output or transmission and reception of image data, afacsimile function, a printer function, a scanner function, etc., areknown. A conventional multi-function apparatus (MFP) 100 shown in FIG. 1comprises a facsimile control unit (FCU) 101, a printer control unit(PCU) 102, a motherboard 103, a reading unit 104, an image-processingunit 105, a video control part 106, an imaging unit 107, a memorycontrol unit 108, a system controller 109, a random access memory (RAM)110 and a read only memory (ROM) 111. The PCU 102 comprises, as shown inFIG. 2, a memory access control part (IMAC) 121, a network interface(I/F) 122, a system controller 123, a local bus interface (I/F) 124, aparallel bus interface (I/F) 125, a memory group (MEM) 126 and a serialbus interface (I/F) 127.

In the multi-function apparatus (MFP) 100, after the reading unit 104optically reads an image of an original and changes the read image intoa digital image signal, the reading unit 104 outputs the digital imagesignal to the image-processing unit 105. The imaging unit 107 forms areproduction image on a transfer paper based on the digital image signalfrom the video bus control part 106.

The image-processing unit 105 applies various image quality processes,such as correction of image degradation in the reading system of thereading unit 104 and gradation reproduction by an area gradation method,to the image signal, and outputs the processed image signal to the videocontrol part 106. The video control part 106 performs a bus control, andarbitrates an incoming signal from the image-processing unit 105, anoutput signal to the imaging unit 107, an input-and-output signal to thememory control unit 108, and an input-and-output signal with the FCU 101and the PCU 102 which are external application units connected throughthe motherboard 103.

An external extension application unit can connect a plurality ofapplications to the motherboard 103. Each application has a CPU and amemory, and functions as an independent unit. For example, the FCU(facsimile control unit) 101 and the PCU (printer control unit) 102correspond to the applications. Regarding the job using a memory, suchas image rotation by the copy function, after the MFP 100 stores theimage data from the image-processing unit 105 in the memory control unit108 via the video control part 106 and performs image rotationprocessing, the MFP 100 carries out image reproduction in the imagingunit 107 via the video control part 106. The MFP 100 carries out theseries of controls by the system controller 109. On the other hand,regarding a deployment process on the memory of the printer output imageby the PCU 102, the system controller 109 and the memory control unit108 do not use the MFP 100, but uses uniquely the system controller 124and the memory group 126 provided in the PCU 102 shown in FIG. 2.

In the PCU 102 shown in FIG. 2, the system controller 124 controls anoperation of the entire PCU 102 so that the PCU 102 operates as a singleunit as a whole. That is, the memory which can be used by the PCU 102 isonly the memory group 126 inside the PCU 102. Such a composition of thePCU 102 is the same as the FCU 101. If data is sent to the PCU 102 via anetwork, print output request data is taken in the IMAC 121 through thenetwork I/F 122.

When a general-purpose serial bus connection is used, the systemcontroller 123 receives the print output request data supplied to theIMAC 121 via the serial bus I/F 127. Usually, a plurality of kinds ofinterfaces are provided as the general-purpose serial bus I/F 127 so asto cope with interfaces such as USB, IEEE1284 and IEEE1394. The systemcontroller 123 develops the received print output request data to imagedata in an area within the MEM 126. At this time, font data of a fontROM (not illustrated in the figure) connected to the local bus concernedis referred to via the local bus I/F 124 and a local bus.

A serial bus connected to the serial bus I/F 127 is also provided withan interface (I/F) for data transmission with an operation part of theMFP 100 in addition to an external serial port for connection with apersonal computer. Unlike print deployment data, the operation part ofthe MFP 100 communicates with the system controller 123 via the IMAC121.

The system controller 123 controls reception of the processing procedurefrom the operation part and the display of the state of the system onthe display part. The local bus connected to local bus I/F 124 isconnected to the ROM and RAM required for control of the controllerunit. Font data is input through the local bus and used for imagedeployment.

In the above-mentioned conventional multi-function apparatus (MFP), amemory is not used effectively and communization of a control mechanismincluding extended units is not made. That is, each of the facsimilecontrol unit (FCU) and the printer control unit (PCU) has individually asystem control module, a memory module and a memory control module.Accordingly, each control unit performs a similar control separately,and, thereby, effective use of resources is not achieved. Therefore, theapparatus is enlarged, and a cost is increased. Moreover, it isnecessary to improve for increasing a processing speed.

Moreover, in the above-mentioned multi-function apparatus (MFP), inorder to realize a high-quality image by a high-densification of dots,it has been suggested to perform a dot position control of writing. Thisis for the reason that a single dot reproduction with high-density dotsneeds a high technology, and, on the other hand, a stable and smoothgradation can be obtained by concentrating dots. However, depending onthe kind of image, a very thin line, for example, is crushed when dotsare concentrated. In such a case, it is necessary to perform a signalprocessing to cause a single isolated dot reproduced.

On the other hand, it has been suggested to attain a high quality outputimage by performing writing with a higher density than a readingdensity. For example, a process has been suggested to read by 600 dpiand write by 1200 dpi. If a single pixel of 600 dpi is converted intofive values by halftone processing, the pixel data becomes 33-bit data.If this data is converted into a binary value of 1200 dpi by ahigh-density conversion, the data becomes 4-bit data. That is, an amountof image data increases by the high-densification conversion.Furthermore, when information of the above-mentioned pixel arrangementis added, the amount of information increases further and there is aproblem in that a processing speed is decreased. Japanese Laid-OpenPatent Application No. 6-12112 discloses a technology to reduce anamount of data by encoding image data. However, the technology disclosedin Japanese Laid-Open Patent Application No. 6-12112 relates to anexchange of image data with external equipment, such as a printer or afacsimile machine, and does not relate to encoding of high-density datafor data transmission inside a processing apparatus.

SUMMARY OF THE INVENTION

It is a general object of the present invention to provide an imageprocessing apparatus and method in which the above-mentioned problemsare eliminated.

A more specific object of the present invention is to provide animage-processing apparatus and method in which a central-controlledmemory is shared by a plurality of functions so as to effectively usethe memory.

Another object of the present invention is to provide animage-processing apparatus and method which is inexpensive and small andcan produce a high-quality image by carrying out a density conversion soas to match the pixel density.

A further object of the present invention is to provide animage-processing apparatus and method and a recording medium storing aprocess program to carry out the image-processing method, which canefficiently perform data processing by encoding high-density data withinthe image-processing apparatus.

In order to achieve the above-mentioned objects, there is providedaccording to one aspect of the present invention an image-processingapparatus comprising: a memory storing a digital image signal; a memoryaccess control part entirely managing all accesses to the memory withrespect to the digital image signal; and an image processing partconverting the digital image signal stored in the memory into an outputimage signal to be supplied to an imaging unit outputting a visibleimage based on the output image signal so that a pixel density of theoutput image signal is higher than a pixel density of the digital imagesignal read from the memory and an amount of the output image signal isless than an amount of the digital image signal stored in the memory.

According to the above-mentioned invention, the central controlledmemory is shared by a plurality of functions so as to effectively usethe memory, and a high-quality image can be produced by carrying out adensity conversion so as to match the pixel density. Additionally, theimage-processing apparatus according to the present invention isinexpensive and small and can effectively use resources.

The image-processing apparatus according to the present invention mayfurther comprise a programmable operation processor processing thedigital image signal so as to reduce a number of quantization steps ofthe digital image signal and store the digital image signal having areduced number of quantization steps in the memory. Accordingly, anarbitrary image processing can be applied to the read image data so asto improve the image quality and also the data transmission efficientcan be improved.

Additionally, the memory access control part may arrange pixels of theoutput image signal in a square area while preventing generation of anisolated single pixel of black or white when converting the digitalimage data into the output image data. Accordingly, the number of pixelscan be increased in both the main scanning direction and the subscanningdirection at the same time, which results in a high efficiencypixel-density conversion.

Further, the memory access control part may include a pixel densityconversion part converting the digital image signal by using the memory;and the image processing part may include an edge smoothing partsmoothing an edge of black pixels and white pixels, wherein the edgesmoothing part is controlled, separately from the pixel densityconversion part, by a write-in control performed by the imaging unit.Accordingly, the smoothing process depending on the characteristics ofthe imaging unit and the pixel-density conversion are performedindependently from each other so as to reduce a processing time of thepixel-density conversion. Thus, a further higher-quality image can beproduced for a short time.

Additionally, the output image signal may be transmitted from the memoryto the imaging unit in a form of code data, and the imaging unit mayconvert the code data into pixel data so as to perform an image outputunder the write-in control of the imaging unit. Accordingly, The datatransmission from the memory to the imaging unit can be effectivelyperformed in a short time, and the data bus is effectively used. Thus, afurther efficient processing can be performed at a high speed.

Additionally, transmission of the code data from the memory to theimaging unit is performed in synchronization with a signal indicating awrite-in line of the code data. Accordingly, the image data can betransmitted only when it is needed in accordance with a request by theimaging unit. Thus, a bus occupancy time can be reduced, which improvesa total efficiency of memory use and bus use.

Additionally, there is provided according to another aspect of thepresent invention an image-processing method comprising the steps of:storing a digital image signal in a memory; entirely managing allaccesses to the memory with respect to the digital image signal; andconverting the digital image signal stored in the memory into an outputimage signal to be supplied to an imaging unit outputting a visibleimage based on the output image signal so that a pixel density of theoutput image signal is higher than a pixel density of the digital imagesignal read from the memory and an amount of the output image signal isless than an amount of the digital image signal stored in the memory.

According to the above-mentioned invention, the central controlledmemory is shared by a plurality of functions so as to effectively usethe memory, and a high-quality image can be produced by carrying out adensity conversion so as to match the pixel density. Additionally, theimage-processing apparatus according to the present invention isinexpensive and small and can effectively use resources.

Additionally, there is provided according to another aspect of thepresent invention a processor readable medium storing program code forcausing an image-processing apparatus to perform an image processing,comprising: program code means for storing a digital image signal in amemory; program code means for entirely managing all accesses to thememory with respect to the digital image signal; and program code meansfor converting the digital image signal stored in the memory into anoutput image signal to be supplied to an imaging unit outputting avisible image based on the output image signal so that a pixel densityof the output image signal is higher than a pixel density of the digitalimage signal read from the memory and an amount of the output imagesignal is less than an amount of the digital image signal stored in thememory.

According to the above-mentioned invention, the central controlledmemory is shared by a plurality of functions so as to effectively usethe memory, and a high-quality image can be produced by carrying out adensity conversion so as to match the pixel density. Additionally, theimage-processing apparatus according to the present invention isinexpensive and small and can effectively use resources.

Additionally, there is provided according to another aspect of thepresent invention an image-processing apparatus having a frame memorycontrolled by a memory controller, comprising: a scanner reading animage so as to produce read image data; a pixel density conversion partconverting the read image data into high-density image data having apixel density higher than a pixel density of the read image data; amemory storing the high-density image data according to a predeterminedarrangement of pixels; a code conversion part converting thehigh-density image data into code data according to a predeterminedconversion code; and an output interface part outputting code data asimage data to an imaging unit forming a visible image based on the imagedata.

According to the above-mentioned invention, since the high-densityimaged data is transmitted by reducing the amount of data by encoding,the data transmission efficiency is improved and a high-speed imageprocessing can be achieved.

In the image-processing apparatus according to the above-mentionedinvention, the code conversion part may decide an ON/OFF position ofpixel data of the image data output from the output interface part, andthe output interface part may change pixel positions of the high-densityimage data based on pixel positions of the read image data. Accordingly,a dot control matching the characteristics of an image can be performedwith a reduced amount of data, and a high-quality image can be produced.

Additionally, the code conversion part may set the pixel positions ofthe high-density image data based on information regardingcharacteristics of the read image data. Accordingly, a dot controlmatching the characteristics of an image can be performed with a reducedamount of data, and a high-quality image can be produced.

There is provided according to another aspect of the present inventionan image-processing method comprising the steps of: reading an image soas to produce read image data; converting the read image data into ahigh-density image data having a pixel density higher than a pixeldensity of the read image data; storing the high-density image data in amemory according to a predetermined arrangement of pixels; convertingthe high-density image data into code data according to a predeterminedconversion code; and outputting code data as image data to an imagingunit forming a visible image based on the image data.

According to the above-mentioned invention, since the high-densityimaged data is transmitted by reducing the amount of data by encoding,the data transmission efficiency is improved and a high-speed imageprocessing can be achieved.

In the image-processing method according to the above-mentionedinvention, the step of converting the high-density image data mayinclude a sep of deciding an ON/OFF position of pixel data of the imagedata, and the step of outputting code data may include a step ofchanging pixel positions of the high-density image data based on pixelpositions of the read image data.

Additionally, the step of converting the high-density image data mayinclude a step of setting the pixel positions of the high-density imagedata based on information regarding characteristics of the read imagedata.

There is provided according to another aspect of the present invention,a processor readable medium storing program code for causing animage-processing apparatus to perform an image processing, comprising:program code means for reading an image so as to produce read imagedata; program code means for converting the read image data into ahigh-density image data having a pixel density higher than a pixeldensity of the read image data; program code means for storing thehigh-density image data in a memory according to a predeterminedarrangement of pixels; program code means for converting thehigh-density image data into code data according to a predeterminedconversion code; and program code means for outputting code data asimage data to an imaging unit forming a visible image based on the imagedata.

According to the above-mentioned invention, since the high-densityimaged data is transmitted by reducing the amount of data by encoding,the data transmission efficiency is improved and a high-speed imageprocessing can be achieved.

In the processor readable medium, the program code means for convertingthe high-density image data may include program code means for decidingan ON/OFF position of pixel data of the image data, and the program codemeans for outputting code data may include program code means forchanging pixel positions of the high-density image data based on pixelpositions of the read image data.

Additionally, the program code means for converting the high-densityimage data may include program code means for setting the pixelpositions of the high-density image data based on information regardingcharacteristics of the read image data.

Other objects, features and advantages of the present invention willbecome more apparent from the following detailed descriptions when readin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a conventional multi-function apparatus;

FIG. 2 is a block diagram of a printer control unit shown in FIG. 1;

FIG. 3 is a circuit block diagram of a multi-function apparatus (MFP)according to a first embodiment of the present invention;

FIG. 4 is a block diagram of an image memory access control part (IMAC)shown in FIG. 3;

FIG. 5 is a block diagram of a memory control part shown in FIG. 4;

FIG. 6 is a block diagram of a video data control part (VDC) shown inFIG. 3;

FIG. 7 is an illustration for explaining a switching control of upperpixels or lower pixels decoded in a selector in the VDC shown in FIG. 6;

FIG. 8 is an illustration showing a system control and a bus connectionin a basic structure of the MFP shown in FIG. 3;

FIG. 9 is an illustration showing the system control and the busconnection of the MFP in a printer mode;

FIG. 10 is an illustration showing a control bus connection of the MFPshown in FIG. 3;

FIGS. 11A is an illustration showing a data compressing operation of theIMAC shown in FIG. 4; and FIG. 11B is an illustration showing a datadecompressing operation of the IMAC shown in FIG. 4;

FIGS. 12A, 12B and 12C are is illustrations for explaining a pixeldensity conversion process applied to read image data by the MFP shownin FIG. 3;

FIG. 13 is an illustration for explaining an example of a codeassignment by the MFP shown in FIG. 3;

FIG. 14 is an illustration for explaining an example of a codeconversion shown in FIG. 13;

FIG. 15 is a block diagram showing data transmission paths of read imagedata when a pixel density conversion process is performed by the MFPshown in FIG. 3;

FIG. 16 is a block diagram showing data transmission paths of binaryvalue image data when a pixel density conversion process is performed bythe MFP shown in FIG. 3;

FIG. 17 is a block diagram of a frame memory and a memory access controlpart (IMAC) in an image processing apparatus according to a secondembodiment of the present invention;

FIG. 18 is an illustration for explaining an operation of a high-densityconversion part of the IMAC shown in FIG. 17;

FIG. 19 is an illustration of an example of an operation performed by acode conversion part of the IMAC shown in FIG. 17;

FIG. 20 is an illustration of another example of the operation performedby the code conversion part of the IMAC shown in FIG. 17;

FIG. 21 is a block diagram of the IMAC and other peripheral partsconfigured to perform an operation to change pixel positions; and

FIG. 22 is an illustration showing an example of data development.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will now be given, with reference to accompanyingdrawings, of preferred embodiments of the present invention.

(First Embodiment)

FIG. 3 through FIG. 16 show an image-processing apparatus and method anda recording medium according to a first embodiment of the presentinvention. FIG. 3 is a circuit block diagram of a multi-functionapparatus (MFP) 1 according to the first embodiment of the presentinvention.

In FIG. 3, the MFP 1 comprises: a reading unit 2; a sensor board unit 3(SBU); a compression/decompression and data interface control part(CDIC) 4; an image-processing processor (IPP) 5; a video data controlpart (VDC) 6; an imaging unit 7, a process controller 8; a random accessmemory (RAM) 9; a read only memory (ROM) 10; a facsimile control unit(FCU) 11; an image memory access control part 12 (IMAC); a memory group(MEM) 13; a system controller 14; an operation panel 15; an externalserial port 16; a RAM 17; a ROM18; and a font ROM 19. The reading unit2, the SBU 3, the CDIC 4, the IPP 5, the VDC 6, the imaging unit 7, theprocess controller 8, the RAM 9 and the ROM 10 are connected to theserial bus 20. The FCU 11, the IMAC 12, the CDIC 4 and the VDC 6 areconnected to the parallel bus 21. Moreover, the IMAC 12, the RAM 17, theROM18, and the font ROM 19 are connected to the local bus 22.

The MFP 1 has various mode functions, such as a scanner mode, a copymode, a facsimile mode, and a printer mode. In the scanner mode or copymode of the MFP 1, a reading unit 2 irradiates a reading light from alight source onto an original and a light-receiving elements, such as acharge coupled device (CCD), which SBU 3 provided through the mirror andthe lens, condense the catoptric light from an original. In the scannermode or copy mode of the MFP 1, the reading unit 2 irradiates a readinglight from a light source onto an original, and converges the readinglight reflected by the original onto a light-receiving element, such asa charge coupled device (CCD) provided to the SBU 3, via a mirror and alens. By carrying out an optoelectric conversion by the light-receivingelement concerned so as to read the original in a primary scanningdirection, a digital conversion of the image signal is carried out bythe SBU 3 so as to produce and outputs the digital image signal to theCDIC 4.

The CDIC 4 controls all transmissions of image data between a functionaldevice and a data bus, and performs data transmission between the SBU 3,the parallel bus 21 and the IPP 5. Moreover, the CDIC 4 performscommunication between the system controller 14, which controls theentire MFP 1, and the process controller 8, which performs processingcontrol to image data. The CDIC 4 transfers the image signal from theSBU 3 to the IPP 5, and the IPP 5 corrects a signal degradation (signaldegradation of a scanner system) in the optical system and thataccompanying the quantization to an optical system. The IPP 5 outputsthe image signal to the CDIC 4 again.

In the image processing, the MFP 1 has a job to accumulate and reuseimage data (read image data etc.) in a memory and a job which is carriedout without accumulating image data in a memory. In an example of thejob to accumulate image data in a memory, the reading unit 2 is operatedonly once, when copying a plurality of originals, so as to store theimage data in the memory, the image data is used a plurality of times byreading the image data stored in the memory. As an example without usinga memory, there is a case in which only one copy of one original iscarried out, for example. In this case, since what is necessary is justto reproduce read image data as it is, it is not necessary to perform amemory access.

When not using a memory, the MFP 1 returns the data, which has beentransmitted to the CDIC 4 from the IPP 5, to the IPP 5 from the CDIC 4as mentioned above. The IPP 5 performs an image quality processing forconverting luminance data of a light-receiving element into areagradation data. The IPP 5 transmits the image data after being subjectto the image quality processing to the VDC 6. The VDC 6 performs a pulsecontrol with respect to the signal which has been changed to the areagradation data so as to perform a post-processing on a dot arrangementand reproduce dots. In the imaging unit 7 as a writing means, areproduction image is formed on a transfer paper. As an imaging unit 7,although units of various record systems can be used, a unit of anelectrophotography system is used, for example.

When performing an additional processing, for example, rotation of animage orientation, synthesis of an image, etc. by using a memory, theMFP 1 sends the data, which has been transmitted to the CDIC 4 from theIPP 5, from the CDIC 4 to the IMAC 12 via the parallel bus 21. The IMAC12 performs an access control of the image data and the MEM 13 under acontrol of the system controller 14. Moreover, the IMAC 12 develops theprint data of the externally connected personal computer (PC) 30.Furthermore, the IMAC 12 performs compression/decompression of the imagedata for effectively using the memory. Namely, the PC 30 is connected tothe IMAC 12, and under control of the system controller 14, the IMAC 12receives the digital print data of the PC 30 and develops the print dataon the MEM 13. After the IMAC 12 carries out the data compression of thedata, the IMAC 12 accumulates the compressed data to the MEM 13.Moreover, after decompressing the accumulated data, which is read fromthe MEM 13 when it is needed, the decompressed data is transferred tothe CDIC 4 via the parallel bus 21. The MFP 1 transmits the datatransferred to the CDIC 4 to IPP 5 from the CDIC 4, and cause the IPP 5to perform the image quality processing for converting the luminancedata of the light-receiving element into area gradation data. The IPP 5transmits the image data after image quality processing to the VDC 6,and performs a pulse control on the signal which has been changed to thearea gradation data by the VDC 6 for the post-processing regarding thedot arrangement and reproducing dots. Then, the IPP 5 forms areproduction image on the transfer paper in the imaging unit 7. That is,by a bus control of the parallel bus 21 and the CDIC 4, the MFP 1performs accumulation of data to MEM13 and various transmissionprocessings of data so as to achieve the function as the MFP 1.

Moreover, the public line (PN) 31 is connected to the FCU 11. The MFP 1realizes facsimile transmission and reception function by utilizing theFCU 11. That is, the MFP 1 transmits the image data read by the readingunit 2 to the IPP 5 as mentioned above at the time of facsimiletransmission. The image data is transmitted to the FCU 11 via the CDIC 4and the parallel bus 21, after a required image processing is performedin the IPP 5. The FCU 11 performs data conversion to a communicationsnetwork, and transmits the data to the PN 31 as facsimile data. At thetime of facsimile reception, the MFP 1 converts the facsimile data,which is transmitted from the PN 31 and received by the FCU 11, intoimage data, and transmits the image data to the IPP 5 via the parallelbus 21 and the CDIC 4. In this case, the IPP 5 does not perform anyspecial image quality processing on the transmitted image data, buttransmits the received image data to the VDC 6. Then, dot rearrangementand pulse control are performed by the VDC 6, and a reproduction imageis formed on the transfer paper in the imaging unit 7. The systemcontroller 14, the operation panel 15, and the external serial port 16,etc. are connected to the IMAC 12. The system controller 14 controls thewhole MFP 1. Various keys, a display part, etc. are provided in theoperation panel 15 so as to perform various instructing operations tothe MFP 1. The system controller 14 performs a basic processing as theMFP 1 and a memory control process processing by controlling each partof the MFP 1 according to instructing operations through the operationpanel 15. Moreover, the MFP 1 has a function to concurrently perform aplurality of jobs such as a copy function, a facsimile transceiverfunction, a printer output function, etc. When processing a plurality ofjobs in parallel, the right to use the reading unit 2, the imaging unit7, and the parallel bus 21 is assigned to the jobs. This assignment iscontrolled by the system controller 14 and the process controller 8.

The process controller 8 controls a flow of the image data. The systemcontroller 14 controls the whole system of the MFP 1, and managesactivation of each resource. A selection of function of the MFP 1 isperformed by a key operation of the operation panel 15. The contents ofprocessing, such as a copy function or a facsimile transceiver function,are set up by the key operation of the operation panel 15.

The system controller 14 and the process controller 8 communicatemutually through the parallel bus 21, the CDIC 4 and the serial bus 20so as to perform a data format conversion for the data interface betweenthe parallel bus 21 and the serial bus 20 in the CDIC 4.

As shown in FIG. 4, the IMAC 12 comprises an access control part 41, asystem I/F 42, a local bus control part 43, a memory control part 44, acompression/decompression part 45, an image editorial part 46, a networkcontrol part 47, a parallel bus control part 48, a serial port controlpart 49, a serial port 50 and direct memory access control parts (DMAC)51–55. The direct memory access control parts (DMAC) 51–55 are providedbetween the access control part 41 and each of thecompression/decompression part 45, the image editorial part 46, thenetwork control part 47, the parallel bus control part 48 and the serialport control part 49.

The IMAC 12 is connected to the system controller 14 through the systemI/F 42 so as to perform transmission and reception of commands and datawith the system controller 14 through the system I/F 42. As mentionedabove, the system controller 14 basically controls the entire operationof the MFT 1. The resource allocation of the memories of the memorygroup 13 is also under management of the system controller 14. Controlof operations of other units is performed in the parallel bus 21 throughthe system I/F 42 and the parallel bus control part 48.

Each unit of the MFP 1 is fundamentally connected to the parallel bus21, and the data transmission and reception to the system controller 14and the memory group 13 are managed by the parallel bus control part 48controlling bus occupancy.

The network control part 47 is connected to a predetermined network NWsuch as a local area network (LAN). The network control part 47 controlsconnection with the network NW, and manages data transmission andreception with external extension devices connected to the network NW.The system controller 14 is not involved in the management of operationsof the extension devices connected to the network NW. The systemcontroller 14 controls the interface on the side of the IMAC 12. Inaddition, the control with respect to 100BT is added in the presentembodiment. The IMAC 12 interfaces the connection with the serial bus 20through a plurality of serial ports 50, and has port control mechanismscorresponding to the number of kinds of busses. Namely, the IMAC 12 hasthe serial ports whose number corresponds to the number of kinds ofbusses such as, for example, USB, IEEE1284 and IEEE1394. The serial portcontrol part 49 performs controls of those ports. Moreover, the serialport control part 49 controls, separately from the external serial port50, the data transmission and reception with the operation panel 15 withrespect to reception of commands and display.

The local bus control part 43 interfaces with the RAM 17 and the ROM 18,which are needed to activate the system controller 14, and alsointerfaces with the local (serial) bus 22 to which the font ROM 19 whichdevelops printer code data is connected. The memory control part 44 isconnected with the MEM 13 so as to interfaces with the MEM13.

The access control part 41 controls operations by carrying out a commandcontrol sent from the system controller 14 through the system I/F 42.Moreover, the access control part 41 performs data control centering onthe MEM 13 by managing a memory access from an external unit. That is,the image data to the IMAC 12 from the CDIC 4 is transmitted through theparallel bus 21, and is taken in the IMAC 12 by the parallel bus controlpart 48. The image data taken in the IMAC 12 leaves management of thesystem controller 14 in the DMAC 54. Thereby, memory access is performedindependently from the system control. The access control part 41arbitrates the access to the MEM 13 from a plurality of units. Thememory control part 44 controls an access operation and a data readingand writing operation to the MEM13.

Moreover, in the IMAC 12, an access from the network NW to the MEM 13 isalso performed by accessing the MEM 13 through the DMAC 53 with the datataken in the IMAC 12. Then, the access control part 41 arbitratesaccesses to the MEM 13 in a plurality of jobs, and the memory controlpart 44 performs reading/writing of data.

Furthermore, the IMAC 12 performs an access to the MEM 13 from theserial bus 20 by accessing the data taken in the IMAC 12 through theserial port 50 by the serial port control part 49 by the DMAC 55. TheIMAC 12 arbitrates accesses to the MEM 13 in a plurality of jobs in theaccess control part 41, and performs reading/writing of data in thememory control part 44. Then, in the MFP 1, if the print data of the PC30 is sent from the network NW or the serial bus 20, the systemcontroller 14 develops print data in the memory area of the MEM 13 usingthe font data of the font ROM 19 on the local bus 22.

In MFP 1, the system controller 14 manages an interface with eachexternal unit. Then, each DMAC 51–55 in the IMAC 12 manages memoryaccess. In this case, since each DMAC 51–55 performs data transmissionindependently, the access control part 41 performs priority attachmentwith respect to the collision of jobs and each access request withrespect to the access to the MEM 13. Accesses to the MEM 13 include anaccess of the system controller, other than the accesses by each DMAC51–55, through the system I/F 42 for bit map deployment of stores data.The data of DMAC to which the access control to the MEM 13 is permitted,or the data from the system I/F 42 is performed by a direct access tothe MEM 13 by the memory control part 44.

The IMAC 12 performs a data processing by the compression/decompressionpart 45 and the image editorial part 46. That is, thecompression/decompression part 45 performs a compression and adecompression of data by a predetermined compression system so as toaccumulate image data or code data efficiently to the MEM 13. The datacompressed by the compression/decompression part 45 is stored in MEM 13by the DMAC 51–55 controlling an interface with the MEM 13.

The IMAC 12 transmits the data once stored in the MEM 13 to thecompression/decompression part 45 through the memory control part 44 andthe access control part 41 by a control of the DMAC. Then, afterdecompressing the compressed data, the IMAC 12 performs a control suchas returning to the MEM 13 or outputting to an external bus.

The image editorial part 46 controls the MEM 13 by the DMAC 51–55 so asto clear the memory area in the MEM 13 and perform a data processingsuch as a rotation of an image or a synthesis of different images.Moreover, the image editorial part 46 performs an address control on thememories of the MEM 13 so as to convert the data to be processed.However, the image editorial part 46 does not perform a conversion ofcode data after being compressed by the compression/decompression part45, or conversion into printer code but performs the above-mentionedimage processing on a bit map image developed on the MEM 13. That is,the compression process for accumulating data effectively to the MEM 13is performed after an image edit is performed by the image editorialpart 46. The memory control part 44 comprises, as shown in FIG. 5, adata path control part 61, the data buffer 62, a request control part63, an input-and-output control part 64, an output I/F 65, an input I/F66, an external memory access control part 67 and a command control part68. The memory control part 44 transmits and receives data between theaccess control part 41 and the MEM 13.

The access control part 41 has an interface with each DMAC 51–55. Theaccess control part 41 receives the command for the intervention to theMEM 13 of the system controller 14 to the MEM 13 and access arbitrationby being connected to the system I/F 42. Thereby, an access to the MEM13 is independently attained for the access request to the MEM 13 of theDMACs 51–55 and the system controller 14. Therefore, reading from theMEM 13 and the writing to MEM 13 are attained. Moreover, the accesscontrol part 41 judges a priority provided from the system controller 14with respect to a plurality of competing read requests or writerequests, and switching a path to the memory control part 44 and theaccess control part 41 by a command control from the system controller14.

Since data maintenance cannot be performed on the DMAC 51–55 which isnot permitted to write in the MEM 13, data input from outside cannot beperformed, and, therefore, a data input operation of external units isprohibited by a control of the system controller 14.

Output data of the DMAC 51–55 or the system I/F 42 of which access tothe MEM 13 is permitted is transmitted to the memory control part 44.Moreover, a command of the permitted system controller 14 is alsotransmitted to the memory control part 44.

The memory control part 44 temporarily stores in the data buffer 62 thedata transmitted from the access control part 41. The data path controlpart 61 switches a path to the output I/F 65 to the MEM 13. The memorycontrol part 44 performs the control of the path by decoding the commandby the system I/F 42 and activating the access of the output I/F 65 tothe MEM 13 by the input-and-output control part 64.

The memory control part 44 generates a MEM control signal by theexternal memory access control part 67 based on control system data sentfrom the DMACs 51–55 or the system controller 14 so a to perform anaddress control of the MEM 13. The memory control part 44 transmits thedata and the MEM control signal to the MEM 13, and stores the data inthe MEM 13. The memory control part 44 reads the data stored in the MEM13. That is, based on the control system data from the DMAC 51–55 or thesystem controller 14 to which an access to the MEM 13 is permitted, thememory control part 44 generates the MEM control signal by the externalmemory access control part 67, and performs an address control of theMEM 13. Then, the memory control part 44 transmits a control signal tothe MEM 13 from the external memory access control part 67, and performsa memory read-out processing, and taken in the access data through theI/F 66. The memory control part 44 temporarily stores the data, which istaken in from the MEM 13, in the data buffer 62 by the data path controlpart 61, and transmits the data to a requesting channel via the accesscontrol part 41.

The VDC6 comprises, as shown in FIG. 6, a decoding part buffer 71, aline buffer 72, a selector 73, a 9-line buffer 74, an image matrix 75 ofa 9-line×3 pixels, a jaggy correction part 76, a processing part 77, anisolated point correction part 78, an error diffusion enhancement 79 adither smoothing part 80, an edge processing part 82 and a selector 83.The jaggy correction part 76 is provided with a correction code part 76a and a RAM 76 b.

The VDC 6 decodes by the decoding part 71 3-bit encoding datatransmitted via the parallel bus 21 from the IMAC 12, and converts thedata into pixel data 2×2 pixels. The VDC 6 stores 2 pixels located inthe lower row of the converted pixel data in the 1-line buffer 72, andtransmits 2 pixels located in the upper row to the selector 73. Theselector 73 switches the decoded upper row pixels or lower row pixels insynchronization with a line synchronization signal, and transmits it tothe image matrix 75 through the 9-line buffer 74. The VDC 6 performs acontrol of switching the upper row pixel and the lower row pixel, asshown in FIG. 7. That is, the VDC 6 requests the IMAC 12 to transmit theencoded data for every two lines. At the first line, the decoded upperrow pixel is chosen as it is, and the 2 pixels of the lower row aretransmitted to the 1-line buffer 72. At the second line which indicatesthe next image line, the VDC 6 reads the previously stored lower rowpixels from the line buffer 72, and uses the pixels for pixelcorrection.

In addition, the code data treats the pixel information regarding twolines, and latter-part pixels are stored in the line memory whileprinting the head line. Accordingly, the transmission from IMAC 12 canbe performed every other line, and at a line which is not required totransmit, the MFP 1 opens the parallel bus 21 to other processing unitsso as to improve the data transmission efficiency of the MFP 1.

In the VDC 6, the image matrix 75 creates 13-pixel delay data in themain scanning direction from data of nine lines, respectively, so as tocreate a 9-line×13-pixel two-dimensional matrix. Although the VDC 6accesses the matrix data simultaneously so as to carry out a binaryvalue/multi-value conversion processing, the VDC 6 performs, withrespect to an edge processing, a process with data on 1 line withoutusing a two-dimensional image matrix.

In the jaggy correction part 76 the correction code part 76 a performspattern matching using the arrangement data of the image matrix 75 so asto generate 12-bit code data, and input the code data to the address ofthe RAM 76 b. The RAM 76 b is for image correction, and outputs imagecorrection data corresponding to an input code. It should be noted thatthe correction data is separately downloaded to the RAM.

The isolated point correction part 78 detects an isolated point bypattern matching in an image area of 9×13 containing an attention pixel.By removing the pixel corresponding to an isolated point or addingpixels to the isolated point within two-dimensional range, theprocessing part 77 constitutes a set of pixels which are not isolatedand outputs the set of pixels to the selector 83. In addition, a modechange is available as to whether a masking is carried out by theprocessing part 77 or whether pixels are added to the circumference.That is, in a case of an isolated dot, depending on the processconditions of a write-in system, there may be a case in which a dot canbe reproduced and a case in which a dot cannot be reproduced, and, thus,unevenness occurs in concentration in an input concentration area, anddegradation of image quality is caused. Therefore, a mode change isperformed so as to not strike any dot or increase a dot density to therange in which dots can be reproduced stably. The isolated pointcorrection part 78 sets up a central pixel as an attention pixel withinthe range of the image matrix 75 of 9×13 in detection of an isolatedpoint. As an object of a judgment of whether to be an isolated pointregarding the attention pixel concerned, the isolated point correctionpart 78 judges relation to circumference pixels by pattern matching soas to judge an isolated point. The error diffusion enhancement part 79smoothes a texture by a band-pass filter holding a line image so as togenerate a phase signal based on the pixel row of the main scanningdirection, and outputs the phase signal to the selector 83.

The dither smoothing part 80 performs low path filter processing of 5×5,7×7 and 9×9 on a binary value dither pattern so as to approximatelyconvert into a multi-value signal in false, and outputs the ditherpattern to the 2-dot processing part 81. Namely, by applying eachsmoothing filtering processes of 5×5, 7×7, and 9×9 to the9-line×13-pixel image matrix 75, the dither smoothing part 80 removes ahigh-band signal component from the input data which is a 1-bit binaryvalue signal, and outputs it to the 2-dot processing part 81.

The 2-dot processing part 81 performs equalization between adjacentpixels on the signal approximately multi-valued signal so as to generatephase information, and outputs the phase information to the selector 83.That is, the 2-dot processing part 81 equalizes the pixels, which havebeen smoothed by the dither smoothing part 80, between EVEN pixels andODD pixels in the main scanning direction. A phase signal isdistinguished although this value is an average value. That is, an EVENpixel is made a right phase and an ODD pixel a left phase so as to form2-dot image data. Although the 2-dot processing part 81 outputs thephase data to the selector 83 as it is, the 2-dot processing part 81performs a level conversion on concentration data so as to convert intodata having a 4-bit width.

The selector 83 selects an image path according to the mode, and outputsthe data, which has been converted into a multi-value from a binaryvalue, as 6-bit data having 4 bits for concentration and 2 bits forphase. The edge processing part 82 performs an edge smoothing processingon data on one line, and outputs the smoothed data to the selector 83.That is, the two-dimensional image matrix 75 is not needed for theprocess in the edge processing part 82.

A description will now be given of an operation of the presentembodiment. The MFP 1 according to the present embodiment effectivelyuses the MEM 13 by sharing the MEM 13 with each unit.

That is, in the MFP 1, as shown in FIG. 6, the IMAC 12, the CDIC 4 andthe VDC6 are connected to the parallel bus 21, and data transmissionbetween the IMAC 12, the CDIC 4, and the VDC 6 is performed through theparallel bus 21. Moreover, the CDIC 4, the VDC 6, the process controller8, etc., are connected to the serial bus 20, and data transmissionbetween the CDIC 4, the VDC 6, and the process controller 8 is performedthrough the serial bus 20. Image data and a command code are transmittedthrough the parallel bus 21 in a predetermined format withoutdiscrimination. In the MFP 1, although the system controller 14 managesthe whole control, a direct control of functional modules other than acontrol of memory related units and the parallel bus 21 is performed bythe process controller 8. The process controller 8 is controlled by thesystem controller 14. The process controller 8 and the system controller14 communicate with each other according to a relationship between amaster and a slave. Format conversion between parallel data and serialdata is performed in the CDIC 4 or the VDC 6.

The MFP 1 transmits a control signal of the system controller 14 to theparallel bus 21 through the parallel bus control part 48 in the IMAC 12.After taking in the command data on the parallel bus 21, the CDIC 4converts parallel data into serial data, and transmits the converteddata to the serial bus 20. The process controller 8 connected to theserial bus 20 receives the command data, which is sent from the systemcontroller 14, from the serial bus 20. The process controller 8 controlsthe CDIC 4 and the VDC 6 via the serial bus 20 based on instructions ofthe command data. The system controller 14 carries out a system controlindependently from the process controller 8, while the processcontroller 8 controls the CDIC 4 or the VDC 6.

The MFP 1 has various functional modes, such as a copy mode, a printermode or a facsimile mode. In the printer mode, the MFP 1 serves as aconnection composition as shown in FIG. 9. Namely, similar to the caseof FIG. 8, the IMAC 12 and the VDC 4, which are connected to the systemcontroller 14, are connected to the parallel bus 21. The VDC 4 and theprocess controller 8 are connected to the serial bus 20. Therefore, ascanner processing system does not need the CDIC 4.

In the printer mode, the MFP 1 supplies the image data for carrying outa print output to the IMAC12 from the PC 30 connected to the network NWor the general use serial bus 20. After image data is developed on a bitmap in the IMAC 12, the image data is transmitted from the IMAC 12 tothe VDC 6 via the parallel bus 21. The MFP 1 transmits a control commandof the VDC 6 from the system controller 14 to the VDC6 via the IMAC 12.After the control command is converted into serial data in the VDC 6,the control command is transmitted to the process controller 8 via theserial bus 20. Then, MFP 1 shifts to a write-in control by the processcontroller 8. The MFP 1 carries out a control based on a route as shownin FIG. 10. That is, the MFP 1 uses a data path of exclusive use withoutgoing the data transmission from the CDIC 4 to the VDC 6 via theparallel bus 21 so s to effectively use the parallel bus 21 and improvethe performance of the entire MFP 1. Basically, the performance isimproved by the role assignment between the system controller 14 and theprocess controller 8. By the process controller 8 serving as acoprocessor of the system controller 14, a write-in control and animage-processing control centering on the imaging unit 7 are performed.In performing a data compression/decompression operation, as shown inFIGS. 11A and 11B, the MFP 1 performs a compression/decompressionprocessing using the compression/decompression part 45 of the IMAC 12,the data path control part 61 of the memory control part 44, and theDMAC 51. The compression/decompression part 45 is provided with acompressor 45 a and a decompressor 45 b, which are used by beingswitched between compression and decompression. The DMAC 51 is providedwith the DMAC 51 a for images and the DMAC 51 b for codes, which areused by being switched between compression and decompression. That is,the MFP 1 avoids a collision of data on the DMAC 51 by using differentchannels of the DMAC 51 for the access to MEM 13 based on image data andcode data.

When compressing image data (encoding), as shown in FIG. 11A, the MFP 1takes in the image data from the MEM 13 by DMAC 51 a for images throughthe memory control part 44 and the access control part 41. The MFP 1compresses the image data by encoding by eliminating the redundantcorrelation information between pixels by the compressor 45 a of thecompression/decompression part 45. The MFP 1 transmits the encoded datato the DMAC 51 b for codes by the data path control part 61, and storesencoded data in the MEM 13 under the intervention of the memory controlpart 44 after an access control. When decompressing (decoding)compresses data, as shown in FIG. 11B, the MFP 1 takes in the encodeddata from the MEM 13 by the DMAC 51 b for codes through the memorycontrol part 44 and the access control part 41. The MFP 1 decompressesthe encoded data by encoding by complementing the correlationinformation between pixels by the decompressor 45 b. The MFP 1 transmitsthe decoded image data to the DMAC 51 a for images by the data pathcontrol part 61. After an access control, the MFP 1 stores the imagedata in the MEM 13 under the intervention of the memory control part 44,or transmits the image data to an external bus from the parallel buscontrol part 48, the network control part 47, or the serial port controlpart 49 without passing though the DMAC 51 a for images. When performingpixel density conversion, the MFP 1 shares the process to the IMAC 12and the system controller on the MEM 13 that is shared by the whole MFP1. A smoothing processing depending on a footer engine characteristic isassigned to the VDC 6. For example, when converting into a twice pixeldensity in each of the main scanning direction and the subscanningdirection by a pixel density conversion, the data to be subjected to thepixel density conversion may include read image data, facsimile data andthe digital data from the PC 30. In a case of read image data, the MFP 1performs a dot rearrangement after the density conversion by the IPP 5,which is a programmable operation processor, to the image datamaximum-quantized to the number of bits smaller than the number ofquantization bits by the SBU 3. In a case of facsimile data or imagedata from PC 30, the MFP 1 performs a dot rearrangement after performinga density conversion with respect to binary value data.

That is, in the case of the read image data, the MFP 1 quantizes theanalog data of an image, which is read by the light-receiving element ofthe SBU 3, into 8-bit/pixel by the SBU 3, and applies an imageprocessing by the IPP 5. In the MFP 1, although the IPP 5 performs agradation processing such as an error diffusion processing so as toreconstruct an image according to an area gradation supposing a transferpaper output, a processing algorithm and a setting parameter are carriedout programmably, and an operation processing is performed so as toachieve a highest image quality and processing speed. The MFP 1quantizes the image data into 3-bit/pixel data having a small bit numberby the gradation processing of the IPP 5, and transmits the quantizeddata to the IMAC 12 via the CDIC through the parallel bus 21. Inaddition, it is assumed that the reading unit 2 is a device of 600 dpiin the main scanning direction and 600 dpi in the subscanning direction,and the imaging unit 7 has a high definition plotter printable by 1200dpi in the main scanning direction and 1200 dpi in the subscanningdirection. The MFP 1 accumulates the image data transmitted to the IMAC12 in the MEM 13.

As shown in FIG. 12A, a 600 dpi×600 dpi×3 bits image is accumulated inthe MEM 13 managed by the IMAC 12 with respect to a size of an originalto be read. It should be noted that FIG. 12A shows data of a size of Npixel×N pixel. The IMAC 12 carries out a bit map conversion so as toconvert the bit map into a high definition density of 1200 dpi×1200dpi×1 bit, as shown in FIG. 12B. That is, in the image data of lowresolution, 3 bits of concentration information of each pixel areconverted into a pixel density of high resolution. In this case, inresponse to an increase of the number of pixels, concentrationinformation is deleted and is converted into a binary value image. Itshould be noted that FIG. 12B shows an example in which an area of anoriginal the same as the bit map of FIG. 12A is converted intohigh-density data of 2N pixels×2N pixels, although the number of pixelsof FIG. 12A is merely increased in both the main scanning direction andthe subscanning direction. Moreover, the IMAC 12 performs a smoothingprocessing on the bit map stored in the MEM 13. FIG. 12C shows anexample in which a smoothing processing is applied to a binary value bitmap after the density conversion shown in FIG. 12B. In the smoothingprocessing, the binary value data is again converted into multi-valuedata so as to reproduce fine pixels.

It should be noted that, in FIG. 12C, thin black dots (circle ofhatching) indicate pixels interpolated by a pattern matching processingalthough consideration is not give to a multi value processing. A cornerof the central part, which is angled in FIG. 12B, is subjected to apattern matching processing so as to carry out a correction processingto form smooth edges.

In addition, when a record engine of the imaging unit 7 is a laserwrite-in type, a pulse width and a laser power to 1 pixel is changed soas to carry out a multi-value writing in which an interval of 1 pixel isdivided. Thereby, the above-mentioned recording, which correctlyreproduces the bit map data which has been subjected to the pixeldensity conversion and the smoothing processing, can be performed.Moreover, in a case in which the imaging unit 7 corresponds to a recordengine which injects droplets of ink such as an inkjet printer, amulti-value level can be reproduced by recording an image by controllingan amount of ink.

The MFP 1 performs a density conversion also on facsimile data or binaryvalue data from the PC 30. Since gradation data is not assigned to 1pixel with respect to the facsimile data or binary value data from thePC 30, dots are rearranged based on arrangement of circumference pixelsafter carrying out a density conversion. However, practically, there isno problem even if simple expansion is applied in the main scanningdirection and the subscanning direction. Since a high-resolutionprocessing with respect to edges is assigned to the smoothingprocessing, there is no need to perform a pattern matching processing inthe IMAC 12, thereby carrying out a high-speed pixel conversion.

That is, supposing FIG. 12A shows a bit map of a binary value image of600 dpi×600 dpi×1 bit from the PC 30, each pixel in the bit map issimply doubled in both the main scanning direction and the subscanningdirection so s to convert into a pixel density of 1200 dpi×1200 dpi×1bit. With respect to the smoothing processing shown in FIG. 12C, similarto the read image data, the imaging unit 7 commonly processes the imagedata irrespective of whether the image data is of a copy mode, afacsimile mode or a printer mode. After converting the bit map on theMEM 13 into the output pixel density of the record engine of the imagingunit 7, the bit map data is treated as bit map data independent of theinput device.

Density conversion and code assignment is performed in the dotprocessing, as shown in FIGS. 13 and 14. In the density conversion, acontrol of 1 dot corresponding to an isolated pint of which dotreproducibility depends on the record engine of the imaging unit 7 isassigned to the smoothing processing. Moreover, a dot arrangement isperformed by the density conversion so that an isolated 1 dot of whiteor black is not formed.

For example, when rearranging 1 pixel of 600 dpi to 4 pixels of 1200dpi, the 4 pixels are arranged in a square area so as to form 2×2 pixelsin the main scanning direction and the subscanning direction. In thiscase, there are only six arrangements of the dots which can be taken,that is, all white, all black and an arrangement in which a pair of twodots are formed. Two consecutive pixels in the a diagonal directionshall not be permitted, and a control of 1-dot in each of the mainscanning direction, the subscanning direction and the diagonal directionis assigned to the smoothing processing.

A direction of connection of the pixels is beforehand taken intoconsideration at the time of the density conversion by the IMAC 12 sothat the pattern matching by the smoothing processing can be carried outeasily at a high speed. That is, in the original pixel of 600 dpi shownin FIG. 13, a code 0 is assigned to all whites, a code 5 is assigned toall blacks, and codes 1 to 4 are assigned to four kinds of arrangementof a pair of two pixels in vertical and horizontal directions.Therefore, the number of generated patterns after the density conversionis six, and all generation patterns can be represented by 3 bits. Changein the amount of data in this pixel density conversion is as follows.Namely, as for the read image data, image data corresponding to the sizeof a read original is transmitted to the IMAC 12 with a small value(less than 8 bits) from the IPP 5. With respect to the size of the readoriginal, a generated pattern is 600 dpi×600 dpi×3 bit, and the pixeldensity conversion with respect to the same size of the original becomes((1200 dpi×1200 dpi)/4)×3 bits. Here, the reason for dividing by “4” isto assign all 4 pixels to a 3-bit code.

If a ratio of the two above-mentioned equations is taken, the ratio ofthe data transmitted to the VDC 6 from the MEM 13 to the datatransmitted to the MEM 13 from the IPP 5 becomes “1” which indicates thesame amount of data. As compared to a case where the converted data istransmitted to the VDC 6 as it is, the amount of data is reduced tothree quarters, thereby improving transmission efficiency. Therefore,when a small value level from the IPP 5 is greater than 3 bits, thetransmission efficiency from the MEM 13 to the VDC 6 is relativelyimproved. Moreover, although the transmission efficiency to the VDC 6deteriorates relatively when the small value level is less than 3 bits,the amount of data can be reduced to three quarters than a case in whichthe converted pixels of 1200 dpi×1200 dpi is transmitted without change.

The above-mentioned example is the case of read image data. In a case offacsimile data or print data from the PC 30, an amount of data of thetransmission code after pixel density conversion can be reduced to threequarters than directly transmitting the data, thereby improving thetransmission efficiency.

FIG. 14 shows an example of a case in which a pattern matching iscarried out in a 3×3 pixel area of 600 dpi×600 dpi. In FIG. 14, athin-color pixel (pixel indicated by a hatched circle) positioned in thecenter of 3×3 pixels is an attention pixel. In FIG. 14, the attentionpixel is converted into 2×2 pixels of 1200 dpi×1200 dpi. That is, inFIG. 14, when the attention pixel is located on an edge and three pixelsexist on the right side, the attention pixel is converted into twopixels which are consecutively arranged in the right part in thevertical direction, and a code 2 is assigned thereto. When the attentionpixel is located on an edge and three pixels exist on the left side, theattention pixel is converted into two pixels which are consecutivelyarranged in the left part in the vertical direction, and a code 4 isassigned thereto. When the attention pixel is located on an edge andthree pixels exist on the lower side, the attention pixel is convertedinto two pixels which are consecutively arranged in the lower part inthe horizontal direction, and a code 3 is assigned thereto. When theattention pixel is located on an edge and three pixels exist on theupper side, the attention pixel is converted into two pixels which areconsecutively arranged in the upper part in the horizontal direction,and a code 1 is assigned thereto. When the attention pixel is located asa convex pixel in any directions, the attention pixel is converted intoall black pixels, and a code 5 is assigned thereto. When the attentionpixel is located as a concave pixel in any directions, the attentionpixel is converted into all white pixels, and a code 0 is assignedthereto. It should be noted that these patterns are examples and a codeis assigned to each of pixel arrangements which can be formed. A pixeldensity conversion is performed by the system controller 14 with respectto image data in the MEM 13 by referring to corresponding pixels bymemory access of the IMAC 12.

In the above-mentioned data processing, data transmission is performedalong the path course of data transmission shown in FIGS. 15 and 16.FIG. 15 shows the data transmission path in the case of the pixeldensity conversion and the edge smoothing processing applied to the readimage data, which is an example of 600 dpi read and 1200 dpi write.

In the case of read image data, as indicated by a data transmission path(1) shown in FIG. 15, the read image data of 600 dpi×600 dpi, which isread by the light-receiving element of the SBU 3 and is converted intodigital data, is transmitted to the IPP 5. In the IPP 5, the read imagedata is re-quantized into a small value of 3 bits/pixel. The quantizeddata is stored in the MEM 13 via the CDIC 4, the parallel bus 21 and theIMAC 12. In the IMAC 12 and the system controller 14, the read imagedata stored in the MEM 13 is density-converted into a binary value imageof 1200 dpi×1200 dpi in the IMAC 12 and the system controller 14, and acode of 3 bits is assigned. The above processing is performed so as togrouping four pixels and assign a code, and the amount of data isreduced rather than directly treating as bit data. As indicated by adata transmission path (2) shown in FIG. 15, the converted data istransmitted from the MEM 13 to the VDC 6 via the IMAC 12, the parallelbus 21 and the CDIC 4. In the above-mentioned data transmission, thereis no change in the amount of data on the data transmission course (1),and the transmission efficiency of the parallel bus 21 does not decreasedue to a highly densification. Then, as mentioned above, the code datatransmitted to the VDC 6 is decoded in the VDC 6. Then, after correctingthe image data to a high print quality by applying the edge smoothing,the record output of the image is carried out by the imaging unit 7.

FIG. 16 shows a data transmission path in a case in which binary imagedata, which is facsimile data or print data from the PC 30, is subjectedto a density conversion. In the case of binary value image data, asindicated by a data transmission path (3) shown in FIG. 16, thefacsimile received binary value image data is developed on the MEM 13via the IMAC 12. On the other hand, the print data from PC 30 isdeveloped on the MEM 13 via the IMAC 12, as indicated by a datatransmission path (4) shown in FIG. 16. The binary value bit map datadeveloped on the MEM 13 via the data transmission path (3) or (4) isdensity-converted into 1200 dpi×1200 dpi which is the resolution of therecord engine of the imaging unit 7. In this case, the image data isconverted into code data corresponding to two consecutive pixels whichdoes not generate an isolated single dot of white or black so as toreduce the amount of data transmitted to the parallel bus 21. The bitmap data is transmitted from the MEM 13 to the VDC 6 through theparallel bus 21, as indicated by a data transmission path (5) shown inFIG. 14. The VDC 6 decodes the transmitted code data, and performs anedge smoothing processing on the binary value bit map image so as tocarry out a record output by the imaging unit 7.

Thus, MFP 1 according to the present embodiment temporarily stores inthe MEM 13 the digital image signal, which is generated by convertingread image data of an original into digital data, or the digital imagesignal which is generated digitally. The, the image signal stored in theMEM 13 is processed to generate an output image signal, which can berecord output by a write-in control of the imaging unit 7. At this time,an access of the digital image signal to the MEM 13 is totally managed.Moreover, when a pixel density conversion is performed to increase apixel density of the digital image signal stored in the MEM 13, theamount of transmission data is reduced.

Therefore, the central-controlled MEM 13 is shared by a plurality offunctions, which results in an effective use of the MEM 13. Moreover,the density conversion can be carried out so that the converted datamatches the pixel density. Moreover, resources can be used effectivelyby an inexpensive and small MFP 1, and a high-definition image can begenerated.

Moreover, the MFP 1 according to the present embodiment stores imagedata in the MEM 13 after applying an arbitrary process to the digitalimage signal, which is read from an original and digitally converted, bythe IPP 5 which is a programmable operation processor so as to changethe read image data to the number of quantization steps less than thenumber of read quantization when reading Therefore, an image quality canbe improved by applying an arbitrary process to the read image data, andalso the data transmission efficiency to the MEM 13 can be improved.

Furthermore, when the MFP 1 according to the present embodiment convertsa low-density single dot into a plurality of high-density pixels, theMFP 1 arranges the converted high-density pixels in a square area whilepreventing generation of an isolate black or white pixel. Therefore, thenumber of pixels in the main scanning direction and the subscanningdirection can be increased simultaneously, and a high pixel densityconversion of high conversion efficiency can be achieved.

Moreover, the MFP 1 according to the present embodiment separatesmutually pixel density conversion processing, which converts a pixeldensity of a digital image signal, and the edge smoothing processing,which smoothes an edge of black pixels and white pixels, and performsthe pixel density conversion processing on the MEM 13, and performs theedge smoothing processing by a write-in control of the imaging unit 7.Therefore, the smoothing processing and pixel density conversiondepending on the characteristic of the imaging unit 7 can be carried outindependently, and processing time for the pixel density conversion canbe shortened. Thereby, a higher definition image can be promptlygenerated.

Furthermore, the MFP 1 according to the present embodiment transmitsimage data in the state code data from the MEM 13 to the imaging unit 7and reverse-converts the image data into pixel data in the imaging unit7, and, thereafter, the pixel data is record output by performing awrite-in control. Therefore, the data transmission from the MEM 13 tothe imaging unit 7 can be more efficiently performed in a short time.

Moreover, a data bus can be effectively used so as to achieve moreefficient process at a higher speed. Moreover, the MFP 1 according tothe present embodiment transmits the code data, which is to betransmitted from the MEM 13 to the imaging unit 7, by reading from theMEM 13 in synchronization with a signal indicating a writing line of thecode data concerned. Therefore, since data can be transmitted accordingto a request of the imaging unit 7 only when required, a bus occupancytime can be shortened and the whole use efficiency and whole bus useefficiency of the MEM 13 can be improved.

Furthermore, programs of the above-mentioned image-processing method isrecordable on a recording medium such as a CD-ROM. The program of theimage-processing method may be read from a recording medium by acomputer connected to the serial bus 20 shown in FIG. 3. Thus, thecentral-managed MEM 13 is shared by a plurality of functions so as toeffectively use the MEM 13, and the MFP 1 can be constructed to performa density conversion so as to match a pixel density.

(Second Embodiment)

A description will now be given, with reference to FIGS. 17 through 22,of an image-processing apparatus and method according to a secondembodiment of the present invention. The image-processing apparatusaccording to the present embodiment has the same whole composition asthe image-processing apparatus according to the first embodiment, and adescription thereof will be omitted.

FIG. 17 is a block diagram showing an outline composition of a framememory and an image memory access control part (IMAC) according to thepresent embodiment. In FIG. 17, data output from a data control part 91of the CDIC 4 is supplied to the IMAC 12, which is a memory controller,via the parallel bus 21 such as a PCI bus. The IMAC 12 is provided witha high-density conversion part 12a and a code conversion part 82. Thehigh-density conversion part 12a converts imaged data of M dpi/N valuessent from the data control part 91 into image data of a stillhigher-density of m dpi/n values (M<m, N>n). The code conversion part 82performs a code conversion process of data from the MEM 13.

A description will be given, as an example of a pixel density conversionaccording to the present embodiment, of a case where a densityconversion of the data of 600 dpi/5 values into data of 1200 dpi/2values is performed.

The binary value data after density conversion is stored in the MEM 13,which consists of a frame memory. When the image data stored in the MEM13 is read and transmitted through the PCI bus again, a transmissionefficiency is raised by encoding image data so as to reduce the amountof data.

FIG. 18 is an illustration showing a processing operation of ahigh-density conversion part 12A in the IMAC 12. In FIG. 18, since thedata is equivalent to a half dot when the data transmitted from a datacontrol part 4A is 2 of 5-value data, four patterns (3 a–3 d) can betaken as a pattern. However, since a dot position control is notperformed here, the data is converted into 4-bit data as it is, and isstored in the MEM 13.

FIG. 19 is an illustration showing a processing operation of a codeconversion part 12B in the IMAC 12. In FIG. 19, considering thearrangement of the data stored in the MEM 13, there are patterns a–d inaccordance with each size. However, there is a regularity in the dotposition control, and when a pixel is enlarged by a dot concentrationmethod so as to strike the dot stably, there is considered a patternindicated by 401. In this example of the regularity, P corresponds to asingle pixel of 600 dpi, and it is represented to enlarge the pixelsfrom positions of d, c, a and b, in that order, when the pixel of 600dpi is divided into four pixels of 1200 dpi and strike each dot at aquarter power. That is, since the position from which a strike a pixelis started is decided by the position of the input image data, the code,which the IMAC 12 supplies, is merely related with the size of data.Therefore, what is necessary is to encode only five patterns (3 bits) ofa instead of 14 patterns (4 bits) including the original patterns of a,b, c and d. Thus, the amount of data, which is transmitted through thebus, decreases, and its transmission efficiency improves.

FIG. 20 is an illustration showing another processing operation of thecode conversion part in the IMAC 12. As indicated by 501, this exampleis a case where a strike of dot is started at the same position in everyposition, which is an advantageous dot formation method to express ahigh resolution for a thin line or the like. Also in this case, in orderto perform a code conversion by a code conversion part 12B, only fivecode patterns (3 bits) are required. Furthermore, there is no need todecide a position from which a dot strike is started according to theimage data position.

FIG. 21 is a block diagram showing an example of a composition in thecase of changing pixel arrangement according to an image data position.In FIG. 21, the data operation part 92 and CDIC 4 are added in additionto the composition shown in FIG. 17. The code data reduced mostefficiently is transmitted to the CDIC 4 through the PCI bus (parallelbus 21). The code-is developed to data by deciding whether to change thepixel arrangement for each position according to information (forexample, 1-bit information indicating whether it is an edge or non-edge)separately sent from the IPP 5.

FIG. 22 is an illustration showing an example of the development of dataencoded as mentioned above. As shown in FIG. 22, although “1110” isobtained if the code is 3 and is developed as it is, a position isshifted so as to obtain “1011” only when a conversion control isperformed. In FIG. 22, when the pixel is arranged by the pattern of c,“1011” is obtained by starting a reading operation of 4-bit “1110” datafrom the position of c.

It should be noted that process programs for performing theabove-mentioned process may be stored in a recording medium such as aCD-ROM, which is readable by a computer connected via the serial bus 20as shown in FIG. 3. Moreover, the process programs may be stored in theROM 10.

The present invention is not limited to the specifically disclosedembodiments, and variations and modifications may be made withoutdeparting from the scope of the present invention.

The present application is based on Japanese priority applications No.2000-29863 filed on Sep. 29, 2000, No. 2000-294698 filed on Sep. 27,2000 and No. 2001-266382 file on Sep. 3, 2001, the entire contents ofwhich are hereby incorporated by reference.

1. An image-processing apparatus comprising: a memory storing a digitalimage signal; a memory access control part entirely managing allaccesses to said memory with respect to the digital image signal; and animage processing part converting the digital image signal stored in saidmemory into an output image signal to be supplied to an imaging unitoutputting a visible image based on the output image signal so that apixel density of the output image signal is higher than a pixel densityof the digital image signal read from said memory and an amount of theoutput image signal is less than an amount of the digital image signalstored in said memory.
 2. The image-processing apparatus as claimed inclaim 1, further comprising a programmable operation processorprocessing the digital image signal so as to reduce a number ofquantization steps of the digital image signal and store the digitalimage signal having a reduced number of quantization steps in saidmemory.
 3. The image-processing apparatus as claimed in claim 1, whereinsaid memory access control part arranges pixels of the output imagesignal in a square area while preventing generation of an isolatedsingle pixel of black or white when converting the digital image datainto the output image data.
 4. The image-processing apparatus as claimedin claim 1, wherein said memory access control part includes a pixeldensity conversion part converting the digital image signal by usingsaid memory; and said image processing part includes an edge smoothingpart smoothing an edge of black pixels and white pixels, wherein saidedge smoothing part is controlled, separately from said pixel densityconversion part, by a write-in control performed by said imaging unit.5. The image-processing apparatus as claimed in claim 1, wherein theoutput image signal is transmitted from said memory to said imaging unitin a form of code data, and said imaging unit converts the code datainto pixel data so as to perform an image output under the write-incontrol of said imaging unit.
 6. The image-processing unit as claimed inclaim 5, wherein transmission of the code data from said memory to saidimaging unit is performed in synchronization with a signal indicating awrite-in line of the code data.
 7. An image-processing method comprisingthe steps of: storing a digital image signal in a memory; entirelymanaging all accesses to said memory with respect to the digital imagesignal; and converting the digital image signal stored in said memoryinto an output image signal to be supplied to an imaging unit outputtinga visible image based on the output image signal so that a pixel densityof the output image signal is higher than a pixel density of the digitalimage signal read from said memory and an amount of the output imagesignal is less than an amount of the digital image signal stored in saidmemory.
 8. A processor readable medium storing program code for causingan image-processing apparatus to perform an image processing,comprising: program code means for storing a digital image signal in amemory; program code means for entirely managing all accesses to saidmemory with respect to the digital image signal; and program code meansfor converting the digital image signal stored in said memory into anoutput image signal to be supplied to an imaging unit outputting avisible image based on the output image signal so that a pixel densityof the output image signal is higher than a pixel density of the digitalimage signal read from said memory and an amount of the output imagesignal is less than an amount of the digital image signal stored in saidmemory.
 9. An image-processing apparatus having a frame memorycontrolled by a memory controller, comprising: a scanner reading animage so as to produce read image data; a pixel density conversion partconverting the read image data into high-density image data having apixel density higher than a pixel density of the read image data; amemory storing the high-density image data according to a predeterminedarrangement of pixels; a code conversion part converting thehigh-density image data into code data according to a predeterminedconversion code; and an output interface part outputting code data asimage data to an imaging unit forming a visible image based on the imagedata.
 10. The image-processing apparatus as claimed in claim 9, whereinsaid code conversion part decides an ON/OFF position of pixel data ofthe image data output from said output interface part, and said outputinterface part changes pixel positions of the high-density image databased on pixel positions of the read image data.
 11. Theimage-processing apparatus as claimed in claim 9, wherein said codeconversion part sets the pixel positions of the high-density image databased on information regarding characteristics of the read image data.12. An image-processing method comprising the steps of: reading an imageso as to produce read image data; converting the read image data into ahigh-density image data having a pixel density higher than a pixeldensity of the read image data; storing the high-density image data in amemory according to a predetermined arrangement of pixels; convertingthe high-density image data into code data according to a predeterminedconversion code; and outputting code data as image data to an imagingunit forming a visible image based on the image data.
 13. Theimage-processing method as claimed in claim 12, wherein the step ofconverting the high-density image data includes a sep of deciding anON/OFF position of pixel data of the image data, and the step ofoutputting code data includes a step of changing pixel positions of thehigh-density image data based on pixel positions of the read image data.14. The image-processing method as claimed in claim 12, wherein the stepof converting the high-density image data includes a step of setting thepixel positions of the high-density image data based on informationregarding characteristics of the read image data.
 15. A processorreadable medium storing program code for causing an image-processingapparatus to perform an image processing, comprising: program code meansfor reading an image so as to produce read image data; program codemeans for converting the read image data into a high-density image datahaving a pixel density higher than a pixel density of the read imagedata; program code means for storing the high-density image data in amemory according to a predetermined arrangement of pixels; program codemeans for converting the high-density image data into code dataaccording to a predetermined conversion code; and program code means foroutputting code data as image data to an imaging unit forming a visibleimage based on the image data.
 16. The processor readable medium asclaimed in claim 15, wherein the program code means for converting thehigh-density image data includes program code means for deciding anON/OFF position of pixel data of the image data, and the program codemeans for outputting code data includes program code means for changingpixel positions of the high-density image data based on pixel positionsof the read image data.
 17. The processor readable medium as claimed inclaim 15, wherein the program code means for converting the high-densityimage data includes program code means for setting the pixel positionsof the high-density image data based on information regardingcharacteristics of the read image data.